Structure relaxation of Mg₆₅Cu₂₅Gd₁₀ metallic glass and its effect on strength

Abstract

To identify the re-arrangement of constituent atoms of an amorphous Mg₆₅Cu₂₅Gd₁₀ alloy happened with annealing, structure relaxation of the alloy was investigated as a function of annealing time at 373 K through extended X-ray absorption fine structure (EXAFS) analysis procedures. To understand the effect of structure relaxation on strength, compression tests were conducted for both the as-cast and the annealed Mg₆₅Cu₂₅Gd₁₀ samples. It is found that short range order around Cu and Gd atoms exhibits different variation trends with increasing annealing time at 373 K, though the structure of the alloy still remains to be amorphous. Based on the fact that the strength of the alloy first exhibits a reduction and then a recovery with annealing time, it is suggested that the enhancement of short range order around Cu should be responsible for the strength reduction, while the enhancement of short range order around Gd should be responsible for the strength recovery.

Keywords

Mg-based metallic glass / structure relaxation / strength / annealing

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